The present invention relates to air belts that include a bag-like portion. The bag-like portion maintains a band-like shape under normal conditions, and which inflates in an emergency, for example when a vehicle collides upon receiving a gas supplied from gas generating means. The present invention also relates to inflatable seat belt apparatuses using the air belts. More specifically, the present invention relates to an air belt in which the length of a bag can be increased and to an inflatable seat belt using the air belt.
Conventionally, seats in vehicles such as automobiles, etc., are usually provided with seat belts. In an emergency, for example when a vehicle collides, the webbings of the seat belts restrain occupants and prevent them from, for example colliding with the vehicle body and being injured. However, in typical seat belts the belts for restraining the occupants are constructed of webbings having a relatively small width, so that the occupants receive a relatively large load when being restrained by the webbings.
Japanese Patent Application Publication No. 6-135293 (incorporated by reference) discloses an inflatable seat belt apparatus including an air belt. The air belt has a webbing which is formed like a bag, and maintains a band-like shape under normal conditions so that the webbing functions similar to a typical seat belt. In an emergency, the webbing inflates upon receiving a gas supplied from gas generating means so that the occupant can be received by the inflated webbing. In such an air belt included in an inflatable seat belt apparatus, the area of the webbing which receives the kinetic energy of the occupant is increased, so that the load can be dispersed. Accordingly, the load applied to the occupant is reduced and the occupant is more effectively protected.
In addition, when the webbing inflates, the length thereof is reduced and the thickness thereof is increased, so that the body of the occupant is pushed against the seat by an amount corresponding to the increase in thickness of the webbing. More specifically, since the length of the webbing is reduced and the thickness thereof is increased, the same effect that occurs in the case in which the webbing is retracted can be obtained. Thus, according to the above-described inflatable seat belt, an initial restraining force as in conventional pretensioners can be obtained.
Typically air belts used in inflatable seat belts (including the air belt disclosed in the above-referenced publication) are constructed as shown in FIGS. 9(a) and 9(b). As shown in the figures, an air belt 1 includes a webbing 2 in which at least the part that comes into contact with an occupant is formed as a bag-like portion, a bag 3 which is inserted in the webbing 2, and a cover 4 which has a tubular shape and which covers the webbing 2. The bag 3 is constructed of an elastic material such as urethane, silicone, etc., which can be formed into a relatively thin sheet, and which has heat resistance and a relatively high strength. The cover 4 is formed of a resin such as polyester, etc.
As shown in FIG. 10(a), the bag 3 is formed in the shape of a thin, long band, and a gas inlet 3a is provided at the lower end thereof. As shown in FIGS. 10(c) and 10(d), the right side portion of the bag 3 is folded in the direction shown in FIG. 10(b) along the folding line xcex1 shown in FIG. 10(a), which extends in the longitudinal direction of the bag 3, at approximately one-third of the width from the right end. In addition, the left side portion of the bag 3 is folded in the direction shown in FIG. 10(d) along the folding line xcex2 shown in FIG. 10(c), which extends in the longitudinal direction of the bag 3 at the center in the width direction thereof in a state shown in FIG. 10(c). Then, as shown in FIG. 9(a), the bag 3 is stored in the webbing 2 in such a manner that the longitudinal direction of the bag 3 is along the longitudinal direction of the webbing 2.
Under normal conditions, the flat, band-like shape of the webbing 2 and the bag 3 is maintained by the cover 4. Part of the webbing 2 which is not the bag-like portion is wound by a seat belt retractor fixed at the bottom of the vehicle body and extends therefrom in a manner similar to, for example, the seat belt apparatus disclosed in the above-referenced publication. In addition, the bag-like portion of the webbing 2 which is extracted from the seat belt retractor is guided toward the occupant by a belt guide which is fixed to, for example, a center pillar, and extends to a tongue connected the webbing 2.
In the air belt 1 having the above-described construction, when a gas supplied from an inflator is injected into the bag 3 via the gas inlet 3a, the bag 3 starts to inflate. Then, the webbing 2 also starts to inflate along with the bag 3, and a sewing thread 5a in a sewn portion 5 of the cover 4 breaks as shown in FIG. 9(c) due to the inflation force of the webbing 2 and the bag 3. Thus, the cover 4 opens so that the webbing 2 and the bag 3 can further inflate.
However, in the above-described folding method of the bag 3, since the bag 3 is folded along only the folding lines xcex1 and xcex2 which extend in the longitudinal direction of the bag 3, the length of the folded bag 3 is long. Accordingly, the bag 3 stored in the bag-like portion of the webbing 2 along the longitudinal direction of the webbing 2 extends over a relatively long area. In order to more effectively inflate the bag-like portion of the webbing 2, the length of the bag 3 must be increased.
When the length of the bag 3 is increased, a part of the bag 3 slides inside the belt guide along with the webbing 2, so that the belt cannot be smoothly extracted and retracted under normal conditions. In addition, since the bag 3 extends to the tongue, the webbing, which is slidably connected to the tongue, the tongue cannot be slid smoothly. Accordingly, there is a problem in that the belt and tongue cannot be easily operated.
In addition, in the bag contained in the conventional air belt, the volume to which the bag inflates is constant irrespective of the deceleration of the vehicle, (i.e., the inertia of the occupant), so that energy absorption effect (EA effect) cannot be obtained. Thus, in order to obtain EA effect, the bag 3 is provided with a vent hole through which the gas is expelled when inflation is completed. However, when the vent hole is provided in the bag 3, the gas inside the bag 3 is expelled in a relatively short time. Thus, in the case in which, for example, a roll-over of the vehicle occurs and the occupant must be restrained for a relatively long time although the deceleration of the vehicle is less than that generated in a vehicle collision, there is a problem with conventional air belts in that there is a reduction in the restraining force applied to the occupant by the air belt.
In consideration of the above-described situation, an object of the present invention is to provide an air belt, in which the length of an inflating portion of a webbing can be increased and a belt and a tongue can be easily operated, and to an inflatable seat belt apparatus using the air belt.
In addition, another object of the present invention is to provide an air belt, in which reduction of the restraining force can be prevented when, for example, a roll-over of an vehicle occurs and the occupant is restrained for a relatively long time, and an inflatable seat belt apparatus using the air belt.
In order to solve the above-described problems, an air belt according to an embodiment of the present invention may include a webbing of which at least a part that comes into contact with an occupant is formed as a bag-like portion, and of which a band-like shape is maintained under normal conditions; a bag which is stored in the bag-like portion of the webbing in such a manner that the longitudinal directions of the bag and the webbing are the same, and which, in an emergency, inflates due to a gas supplied from a gas generator and inflates the bag-like portion of the webbing; and a cover which, under normal conditions, covers a predetermined region including the bag-like portion of the webbing, and which, in an emergency, opens due to an inflation force applied by the bag and the bag-like portion. The bag is stored in the bag-like portion in such a manner that the bag is folded along at least a folding line which is perpendicular to the longitudinal direction of the bag.
In addition, according to an embodiment of the present invention, an inflatable seat belt apparatus using the air belt described above may include a seat belt retractor which, under normal conditions, allows extraction and retraction of the webbing of the air belt, and which, in an emergency, prevents the extraction of the webbing; a belt guide which has a belt guide hole, through which the webbing that extends from the seat belt retractor is inserted in a slidable manner so that the webbing is guided toward the occupant at least under normal conditions; and a tongue which is retained by the webbing and which engages with a buckle fixed to a body of a vehicle. The bag stored in the bag-like portion of the webbing is disposed in a region closer to the occupant than the belt guide, and the bag inflates in at least one of a direction toward the belt guide and a direction toward the tongue.
In addition, according to an embodiment of the present invention, the bag may be provided with a vent hole which is hidden inside the folded bag under normal conditions, and which appears when the bag inflates in the direction toward the belt guide so that the gas inside the bag is expelled therethrough.
In addition, according to an embodiment of the present invention, the bag may be provided with a gas inlet, through which the gas supplied from the gas generating means is injected into the bag, at a position close to the tongue or at a position close to the belt guide.
In the air belt according to an embodiment of the present invention, under normal conditions, the bag is folded along the folding line which is perpendicular to the longitudinal direction thereof. Thus, even when the actual length of the bag is set to a relatively long length, the length of the bag in the state in which it is stored in the bag-like portion of the webbing is reduced.
In addition, since the length of the bag in the stored state is reduced, not only can the actual length of the bag be increased, but there is more freedom to set a length.
In addition, according to an embodiment of the present invention, the bag stored in the bag-like portion of the webbing does not move through the guide hole of the belt guide under normal conditions. Accordingly, under normal conditions, the belt can be smoothly and reliably extracted and retracted, so that the belt can be easily operated.
In addition, since the freedom to set the actual length of the bag is higher, the actual length of the bag can be adequately determined in accordance with the type of the vehicle in which the inflatable seat belt apparatus is mounted.
In addition, when there is large deceleration of the vehicle occurs in an emergency, for example, when the vehicle collides, the bag and the bag-like portion of the webbing start to inflate due to the gas supplied from the gas generator means. Then, the cover opens due to the inflation force, so that the bag and the bag-like portion of the webbing quickly inflate in at least one of the direction toward the belt guide and the direction toward the tongue along the longitudinal direction of the air belt. Thus, the area of the bag-like portion of the webbing which receives the kinetic energy of the occupant is increased, so that the load can be dispersed. Accordingly, the load applied to the occupant is reduced, and the occupant is more effectively protected.
In addition, since a tension is applied to the webbing due to the inertia of the occupant, an EA mechanism of the seat belt retractor is activated by receiving this tension, and the extraction of the webbing starts. The amount by which the webbing is extracted varies with the inertia of the occupant. Thus, due to the extraction of the webbing, the length of the inflating portion of the webbing varies with the inertia of the occupant. Accordingly, the tension of the webbing varies with the amount by which the length of the inflating portion of the webbing is increased. More specifically, the tension of the webbing varies along with the inertia of the occupant, that is, the physical size of the occupant. When the occupant is small, the amount by which the length of the inflating portion of the webbing is increased is small, so that the tension of the webbing is also small. When the occupant is large, the amount by which the length of the inflating portion of the webbing is increased is large, so that the tension of the webbing is also large. Accordingly, the occupant can be more effectively restrained and protected in accordance with his or her physical size.
In addition, since the bag inflates in the longitudinal direction thereof due to the extraction of the webbing, the internal pressure of the bag is reduced as the volume of the bag is increased, and the EA effect can be obtained also by the bag. Especially when the EA effect obtained by the bag and the EA effect obtained by the EA mechanism of the seat belt retractor are combined, the total EA effect can be precisely adjusted.
In addition, irrespective of the physical size of the occupant, the bag-like portion of the webbing inflates to the belt guide and the inflating portion of the bag-like portion is disposed near the side of the head of the occupant. Thus, in the case in which there is a collision with the side portion of the vehicle, the head of the occupant can be more effectively protected.
In addition, according to an embodiment the present invention, the bag may be provided with a vent hole, which is formed at a position such that the vent hole appears when the inflation of the bag in the longitudinal direction thereof is almost completed. Thus, in the case in which, for example, a roll-over of the vehicle occurs and the occupant must be restrained for a relatively long time although the deceleration of the vehicle is less than that generated in a vehicle collision, the vent hole does not appear since the inflation of the bag will not be completed. Accordingly, since only an extremely small amount of the gas inside the bag is expelled, even when the occupant is restrained and protected for a relatively long time, a reduction of the restraining force can be prevented. In addition, in the case in which, for example, the vehicle collides, the effect of absorbing the kinetic energy of the occupant due to the vent hole can be reliably obtained.
In addition, according to an embodiment of the present invention, the bag may be provided with a gas inlet at a position close to the tongue or at a position close to the belt guide. Thus, the gas generating means can be disposed either in a floor portion of the vehicle or in the upper portion of the vehicle. Especially when the gas inlet is disposed at a position close to the belt guide, the gas generator means can be disposed in a roof, a center pillar, a rear pillar, etc., of the vehicle. Thus, the excess space in the vehicle can be effectively utilized, and there is more freedom to choose the position to install the gas generating means.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed.